In practice it has been observed that loose infusion products to be supplied to the volumetric metering devices of machines for packaging these products such as mint, mallow, lime and the like, give rise to various drawbacks during the metering stage as they form bridges along the duct for their supply to the metering chamber of these volumetric devices, thereby preventing metering of some portions and in some cases even failing to advance any portion at all with the consequent stoppage. and therefore the loss of production with a consequent waste of time and packaging material.